Recurrent Squamous Cell Carcinoma In Situ of the Finger

Désirée Ratner, MD

Disclosures

Skinmed. 2003;2(4) 

Introduction

A healthy 60-year-old man presented with a recurrent lesion on his left third finger after surgical treatment 7 years previously (Figure 1). A biopsy reveals squamous cell carcinoma (SCC) in situ. What should be the next steps in the patient's evaluation and management?

Recurrent squamous cell carcinoma in situ of the distal interphalangeal joint of the left third finger, involving the proximal nail fold and extending posteriorly.

A role for human papillomavirus (HPV) has been proposed in a wide range of malignancies, including nonmelanoma skin cancer. While the vast majority of HPV-related cases of non-melanoma skin cancer occur in the setting of epidermodysplasia verruciformis or immuno-suppression secondary to organ transplantation, HPV has also been detected in skin cancers of immunocompetent patients, including SCCs of the fingers and extremities.[1,2,3,4] HPV types 5, 16, and 18 have been positively associated with SCC development, and HPV types 16 and 18 have been shown to lead to cell line immortalization and tumor development in vitro.[5,6] HPV infection with types 5 and 8, among others, also plays a role in the rare inherited condition epidermodysplasia verruciformis, which predisposes affected individuals to develop unusual cutaneous warts and multiple skin cancers. Bowenoid papulosis, consisting of hyperpigmented papules and plaques in a genital distribution, has been specifically linked to HPV types 16 and 18 and exhibits histologic features identical to those of SCC in situ. Verrucous carcinomas, particularly oral and anogenital lesions, are also characteristically HPV positive. Other HPV-related lesions, including common warts and SCCs, have been demonstrated to arise more frequently in immunosuppressed patients on organ transplant regimens, suggesting that viral infection in the context of immunosuppression allows for cell transformation and carcinogenesis.[7] It appears that in most cases, viral infection alone does not lead to cutaneous SCC formation, and that there may be a requirement for cocarcinogens to lead to the formation of cutaneous SCC.

HPV-associated SCC may be found in sunexposed or irradiated areas of the body in nonimmunosuppressed individuals who do not have epidermodysplasia verruciformis, suggesting that ultraviolet or ionizing radiation may play a role as cocarcinogens. HPV has been demonstrated in nongenital lesions of Bowen's disease by in situ DNA hybridization.[8] Recent studies[1,9] have also identified HPV in approximately 30% of SCCs in immunocompetent patients, principally HPV types of known oncogenic potential, with no specific type predominating. These tumors occur most often in periungual or digital locations, as in the patient discussed here, and show a strong association with HPV 16. In one recently published study[4] of HPV-associated digital SCCs, HPV 16 accounted for 89% of the cases in which specific HPV subtypes could be identified. It has been suggested that tumors exhibiting this viral type in this location may in fact have a venereal mode of transmission.[4,10]

After the initial consultation, the patient's biopsy specimen was sent for wide spectrum HPV DNA typing by the in situ hybridization technique. Broad spectrum HPV typing revealed wide spectrum positivity. More specific HPV typing using in situ hybridization techniques revealed positivity for HPV 16.

Recurrent SCC, regardless of site, has a lower response rate to most therapeutic modalities and carries a greatly increased risk of metastasis.[11] While only 5.2% of primary SCCs that develop on sun-exposed skin metastasize, metastatic rates of recurrent SCCs may be as high as 25%. The treatment with the highest reported cure rates for recurrent cutaneous SCC is Mohs micro-graphic surgery.[11,12,13] Mohs micrographic surgery has a 5-year recurrence rate of 3.1% for primary SCCs of the skin at all sites, and a 5-year recur-rence rate of 10.0% for locally recurrent tumors. In contrast, surgical excision has a 5-year recur-rence rate of 8.1% for primary SCCs of the skin at all sites, and a 5-year recurrence rate of 23.3% for locally recurrent tumors. It is important to note, however, that HPV-associated digital SCC is more likely to recur after surgical treatment than cutaneous SCCs in general. In one recent study,[4] the rate of HPV-associated tumor recurrence after Mohs micrographic surgery was 26%, twice the rate calculated from their review of the literature, although the rate of metastasis appears to be low. The authors of this study postulate that this higher rate of recurrence may be due to the persistence of oncogenic HPV at the margins of the tumor-free plane.

Given the fact that this patient's tumor was recurrent after previous treatment, had illdefined clinical borders, was HPV 16 positive, and was located on the distal aspect of the finger (where tissue sparing is critical), the decision was made to perform Mohs micrographic surgery. Since the tumor was located at the proximal nail fold, there was concern that it might have extended locally to involve the lateral nail folds and/or the nail bed. The patient's nail was therefore avulsed completely before undertaking surgical removal of the lesion. Two stages of Mohs surgery were required to clear the tumor, which involved not only the entire extent of the proximal nail fold, but also one lateral nail fold (Figure 2). The patient is now 6 months postoperative, with regrowth of his nail and without evidence of recurrent disease. He will be followed every 3-4 months to monitor for clinical evidence of locally recurrent disease.

Final defect after two stages of Mohs surgery; note the extension of the defect toward one lateral nail fold.

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